appending matrices to binary file - recover with fread and reshape?

Hi!

I need some help on how to recover data from a binary file. I want to store a huge matrix by appending k 1000 x 9000 matrices to a binary file, but I don't know how to recover them in the right order after reading the file using fread and reshape. I want my big matrix to be of size k*1000 x 9000, i.e. the size when concatenating the matrices in the first dimension. Here is what I am doing in principle:

fid = fopen('binFile.bin','a');

for n = 1:k
     data = rand(1000,9000);
     fwrite(fid,data,'double');   
end

bigData = fread(fid,[k*1000*9000],'double');

bigMatrix = reshape(bigData,[k*1000, 9000]);

Thankful for any pointers to solve this!

Answer 1

[Filip]

I figured it out myself:

By transposing the matrix before writing to file, the matrices are appended as expected. Here is the working script in case anyone else experience the same issue:

fid = fopen('binFile.bin','a');
for n = 1:k
     someData = rand(1000,9000);

       % transpose 
       data = someData';

       fwrite(fid,data,'double');   
  end

% slurp up the file with fread
bigData = fread(fid,[k*1000*9000],'double');

% reshape
bigMatrix = reshape(bigData,[k*1000, 9000]);

[kevin sayed]

did you have to transpose the data back after reading it to get the right matrix?